Liquid-solids interface indicator



SEARQH 00M Jan. 5, 1954 E. J. ELLIS 2,

LIQUID-SOLIDS INTERFACE INDICATOR Filed Aug. 8, 1949 2 Sheets-Sheet l lNVENTOli Emma: J 62:15

ATTORNEYS Jan. 5, 1954 E. J. ELLIS 2,664,747

- LIQUID-SOLIDS INTERFACE INDICATOR v Filed Aug. 8, 1949 2 Sheets-Sheet 2 INVENTOR How/mo J. 52:18

W ATTORNEY WW/M Patented Jan. 5, 1954 LIQUID-SOLIDS INTERFACE INDICATOR Edward Jones Ellis, Bartow, Fla., assignor to The Davison Chemical Corporation, Baltimore, Md., a corporation of Maryland Application August 8, 1949, Serial No. 109,123 6 Claims. (01. 73-290) This invention relates to indicating apparatus, and more particularly to apparatus for indicating and recording the level of a liquid-solids interace.

Often in the processing of various materials it is convenient to transfer small particles of solid materials from one vessel to another in the form of an aqueous slurry or pulp. For example, in the treatment of phosphatic sands, the sandy solids in aqueous slurries are pumped into storage bins. The solid materials settle from the liquid in the bins and the liquid is removed from the bins through an over-flow launder. Generally, the supernatant liquid over the settled solids is too turbid for one to observe the level of the liquid-solid interface. It then becomes necessary to make repeated soundings in the storage bin to determine the depth of the solids which have settled in the bin.

It is an object of this invention to provide apparatus for indicating the level of a solid liquid interface in vessels.

Another object of this invention is to provide apparatus for making a continuous record of the level of the solid-liquid interface in a vessel being filled with an aqueous pulp in which the solids are separated from the water.

A further object of this invention is to provide a method and apparatus for instantaneously and continuously observing the level of a liquid-solid interface in a vessel without the necessity of making continuous soundings.

With these and other objects in view, as will become-apparent in the following detailed description, this invention resides in a method and apparatus for determining the level of a liquidsolid interface in a vessel in which a plurality of tubes of different lengths are extended into the vessel and a pilot stream is directed into the upper ends of the tubes. The level of the liquidsolid interface will be indicated by the cessation of flow through one or more of the tubes.

In the drawings:

Figure 1 is a vertical sectional view of a typical bin, equipped with a launder for the over-flow of the liquid in the pulp, showing the indicator of this invention;

Figure 2 is a fragmentary plan view of the storage bin and the indicating apparatus illustrated in Figure 1; and

Figure 3 is a vertical sectional view similar to Figure 1 of a modified form of this invention in which a pressure recorder provides a continuous record of the level of the liquid-solid interface.

Referring to Figure 1 of the drawings, a storage bin, indicated generally by I, is illustrated having an inlet pipe 2 through which an aqueous pulp flows into the bin l A launder 3 extends around the periphery of bin I, near the top thereof to collect the over-flow water fromwhich the solids have settled. An over-flow line 4 is connected with the launder for discharge of the water collected in the launder.

In the particular storage bin shown in the drawings, a nozzle 5 is connected to a water line 6 at the bottom of the storage bin. Water line 6 is provided with any suitable valve 1 for control of the flow of water through line 6. A drain line 8 having an opening positioned adjacent the nozzle 5 is provided at the lower end of storage bin I for removal of the solids from the bin. Drain line 8 is equipped with suitable valve means,

not shown, to prevent flow therethrough while.

the bin is being filled and the pulp is stored in the bin.

Supported at the top of the bin I with its bottom slightly above the level of the upper edge of launder 3 is an indicator box 9. A plurality of tubes H, [2, l3, l4, and I5 successively decreasing in length, extend downwardly from the indicator box 9 into the bin I. The longest tube l I extends substantially to the bottom of the bin and the lower end of the shortest tube I5 is only slightly below the level of the upper edge of launder 3. Any number of intermediate tubes having lengths between the lengths of tubes H and I5 may be provided. The upper end of tubes |ll5 pass through openings in the bottom of indicator box 9 to allow flow from the indicator box through the tubes. Any suitable means, such as welding, of sealing the tubes in the openings in the bottom of the indicator box 9 may be used.

The indicator box 9 is divided into series of cells 16, ll, [8, [9, 2| by partitions 22, 23, 24, 25, extending across the indicator box in the manner shown in Figure 2. The partitions are spaced to provide cells with one tube extending from the bottom of each cell. As shown in the drawings, the height of partitions 22, 23, 2 4, and 25 increases progressively. Actuall it is not necessary to increase the height of the partitions, but the structure illustrated facilitates the use of recording devices.

A water line 26 equipped with a valve 2'! discharges into cell I6 of indicator box 9. The indicator box 9 is equipped at the end opposite the water line 26 with an over-flow 28, for the discharge of the pilot stream when the storage bin is filled with solids above the lower end of tube l5.

For a description of the operation of this in- 3 vention, it will be assumed that bin I is empty at the start of the operation, although in many processes it is desirable to fill the bin with water before the bin is put into use. An aqueous pulp is discharged from inlet pipe 2 into the bin. The

to discharge a pilot stream of water into compartment I6 of the indicator box 9.

As the level of the layer of solids approaches the lower end of tube II, the liquid immediately above the liquid-solids interfacew-ill contain a high concentration of solids and, consequently, has an increased density. The high density of the liquid in the storagebin I, as compared with the density of the pilot streamof water flowing downward through tube II causes the level of the water in the tube to be slightly higher than the upper level of the liquid in the storage bin I. As the level of the liquid-solid interface continues to rise, the elevation of the water from the pilot stream in tube II above the level of the water in the storage bin will become sufficient for the water from the pilot stream to overflow the partition 22 in the indicator box 9 and'flow into cell IT. The reduced rate of flow through tube I I resulting from the water from'the pilot stream over-flowing partition 22 allows the solids to pack around the lower end of tube II, effectively plugging it. The flow of water over the partition 22 is an indication that the level of the liquid-solids interface is near or above the lower end of tube II. Flow over partition 22 -may take place when the lower end of tube II is not completely plugged. The 40 increased density of the liquid in the bin at the bottom of tube Il may only impede flow of the pilot stream sufficiently to cause over-flow of partition 22.

- As the flow of aqueous pulp through inlet pipe 2 continues, the level of the solids will approach the lower end of tube I2. Because of the high density of the liquid immediately above the liquid-solids interface balancing the pilot stream in cell H, the pilot stream will eventually pass overpartition 23 into cell I8 and then through tube I3, thereby giving an indication that the liquid-solids interface is in the region of the lower end of tube I2. Continuous filling of the storage bin with the aqueous pulp will result in the liquid-solids interface rising toward the top of the launder and cause the pilot stream to over-flow successively partitions in the indicator box 9. Eventually, the pilot stream will flow into the cell 2I and out through over-flow 28, to indicatethat the storage bin is full, and that continued introduction of the pulp through inlet pipe 2 will result in large losses through the launder 3 and over-flow line 4.

While the flow of. the pilot stream into any particular cell of. the indicator box 9 is an indication of the height of the liquid-solids interface, in some instances more accurate measurements may be required. If so, the indicator box vide .an accurate indication of the level Of the liquid-solids" interface.

When the solids are drained from the bin through drain line 8, the solid-liquid interface gradually recedes and successively uncovers the tubes from the shortest tube I5 to the longest tube II. Usually, liquid is continually introduced into the bin and overflows through the launder 3 during the draining of the bin. The plug of said sifts out of the lower endiof each tube as it is cleared andthe pilot stream will then pass through the tube. Thus, the level of the liquid-solids interface may be determined when the bin is being emptied as well as when the bin is being filled by observing the flow oi the pilot stream in the indicator box.

A modified form of this invention is illustrated in Figure 3 of the drawings. This form of the invention difiers from the one previously described only in providing means for recording the level of the liquid-solids interface during the filling and draining operations. For this purpose, an air line 3I' extends vertically downward into the indicator box 9 and has its lower end 32 opening into cell I6 below'the upper edge of partition 22. Air line 3I is connected with a suitable source of compressed air, not shown, and is provided with a control valve 33 to regulate the rate of flow of the air through the line 3|. Any conventional pressure recording device 34 is tapped into air line 3| to provide a continuous record of the pressure in air line 3I between control valve 33 and lower end 32 of the air line.

During the filling of the storagebin, air is discharge continuously from the lower end 32' of air line 3| and bubbles up through the liquid in the indicator box. The pressure in air line 3| necessary for the discharge of air from the line will depend upon the level of the liquid in;

indicator box 9 which in turn is dependent upon the level of the liquid-solids interface.

As filling of the storage bin I is continued, the pilot stream may eventually pass over partition 22 into cell II thereby causing the depth of the liquid in the indicator box to be substantially equal to the height of partition 22; The increased depth in liquid in the indicator box increases the pressure in air line 3I-and the recording device 34 makes a continuous record of the pressure: Further increases in the depthof the liquid in the indicator box 9 will cause an increased pressure in air line 3| which will will be recorded by recorder 34. The pressure in air. line 3| may be correlated with the level of the liquid-solids interface by making soundings the first time the bin is filled in the manner described above. I

The novel liquid-solids interface indicator of this invention allows one to determine the level of the interface at a glance. In this manner, the labor required for control of the process is reduced and spills and waste of the materials can be avoided. When the indicator is provided with a recording device, a continuous record is provided thereby permitting greatly improved control of the operation.

The liquid-solid interface indicator described herein is adapted for determining the location of the liquid-solid interface in any suspension in which the suspended solids have a greater density than the medium. The absence of moving parts makes the indicator particularly advantageous when used with alkaline or acid solutions. If the tubes are made of material resistant to corrosion by the suspension, maintenance of the indicator presents no problem,

While this invention has been described in detail with respect to a particular modification of the invention, it is to be understood that the concept of this invention is not limited to those details, but is determined by the scope of the appended claims.

I claim:

1. Apparatus for indicating the level of a liquid-solids interface in a vessel comprising an indicator box having a viewable interior and supported above the liquid level in the vessel, a series of tubes of successively decreasing lengths extending from the indicator box downward into the vessel, partitions in said indicator box of successively increasing heights between the upper ends of said tubes, the longer tube being associated with the shorter partition and each successively shorter tube being associated with the progressively higher partition respectively, means to supply a pilot stream to the indicator box in the region of the longest tube whereby plugging of the tubes with the solids may be observed to ascertain the level of the liquid-solids interface.

2. Apparatus for indicating the level of a liquid-solids interface in a vessel comprising an indicating box supported above the level of the liquid in the vessel and having its interior exposed to view, a series of tubes of successively decreasing length extending into the vessel and having their upper ends opening into the indicator box, partitions in the indicator box dividing it into a successive series of cells into each of which a different one of the tubes opens, and means to supply a pilot stream to the cell from which the longest tube extends, said pilot stream overflowing the partition separating each tube from the next shorter tube as the liquid-solids interface rises to indicate the level of the interface.

3. Apparatus for indicating the level of a liquid-solids interface in a vessel comprising an indicating box supported above the level of the liquid in the vessel, a series of tubes of successively decreasing length extending into the vessel and having their upper ends opening into the indicator box, partitions in the indicator box dividing it into cells into each of which one of the tubes opens, the partitions increasing in height successively from the cell into which the longest tube opens to the cell into which the shortest tube opens, and means to supply a pilot stream to the cell from which the longest tube extends, said pilot stream overflowing the partition separating a tube from the next shorter tube as the liquid-solids interface rises to indicate the level of the interface.

4. Apparatus for indicating the level of a liquid-solids interface in a vessel comprising an indicating box supported above the level of the liquid in the vessel, a series of tubes of successively decreasing length extending into the vessel and having their upper ends opening into the indicator box, partitions in the indicator box dividing it into cells into each of which one of the tubes opens, the partitions increasing in height successively from the cell into which the longest tube opens to the cell into which the shortest tube opens, means to supply a pilot stream to the cell from which the longest tube extends, said pilot stream increasing the depth of liquid in the indicator box and overflowing the partition separating a first tube from the next shorter tube as the liquid-solids interface rises, and means responsive to the depth of the liquid in the indicator box for recording the level of the liquid-solids interface.

5. Apparatus for indicating the level of a liquid-solids interface in a vessel comprising an indicating box supported above the level of the liquid in the vessel, a series of tubes of successively decreasing length extending into the vessel and having their upper ends opening into the indicator box, partitions in the indicator box dividing it into cells into each of which one of the tubes opens, the partitions increasing in height successively from the cell into which the longest tube opens to the cell into which the shortest tube opens, means to supply a pilot stream to the cell from which the longest tube extends, said pilot stream increasing the depth of the liquid in the indicator box and overflowing the partition separating a first tube from the next shorter tube as the liquid-solids interface rises, an air line discharging into the indicator box, and means for recording the pressure in the air line to provide a record of the level of the water in the indicator box.

6. Apparatus for indicating the level of a liquid-solids interface in a vessel comprising an indicator box supported above the level of the liquid in the vessel, a series of tubes extending to successively decreasing depths from the indicator box into the vessel, sump walls within said indicator box forming separate compartments at the upper ends of said tubes, means to supply a pilot stream of liquid to the compartment of the longest tube, whereby plugging of the lower end of a tube with solids is indicated by termination of flow of liquid through said tube.

EDWARD JONES ELLIS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,100,867 Dexter June 23, 1914 2,090,514 Folmsbee Aug. 17, 1937 2,398,958 Pellettere Apr. 23, 1946 2,505,916 Salvesen May 2, 1950 2,528,537 Monnik et al Nov. '7, 1950 

